Very quick -
First contact was with HR - asking basic questions over the phone
Second interview was with HR first then hiring manager (two interviews, same meeting)
Everybody was friendly and relaxed.
Offer was going to be made - however - HR called me and requested permission to contact my current employer. I would get no offer until they contacted my present employer. That was a bit difficult - it essentially burned the bridge - even with the diplomatic conversation that I had with my employer to "prep them". I had to trust/hope that the offer was going to be good enough because the HR contact effectively ended my career at (then) current employer. It all worked out. But that was rough.